"Sans teeth, sans eyes, sans taste, sans everything" is a line from Shakespeare‘s description of the final stage of life made famous in the "All the world’s a stage" monologue from "As You Like It." And it is quoted early on in Barry Levinson’s incoherent adaptation of what is by most accounts a substandard Philip Roth novel, “The Humbling,” to clearly point the way to the film’s themes of ageing, and the diminishment that comes with it. But "toothless, sightless, bland and empty" could also serve as a harsh but pretty accurate description of the film itself: a missed opportunity that squanders the talents of a pretty stacked cast, and trespasses on the audience’s patience and care for its spoiled characters for too long.

Purportedly following a kind of long dark night of the soul for a creatively drained, previously famous theater actor (making this the third Venice title in as many days to use a theatrical backdrop as a means to comment on the nature of creative endeavor) we can see why Al Pacino would be attracted to the material, though. Done right, it could have been a juicy, self-referential, late-career relaunch for a legendary actor who, like his character, has strayed dangerously close to self-parody in recent years, bringing generous helpings of ham to a series of paycheck gigs. But while we still hold out hope of such a return to form for Pacino (in fact, “Manglehorn” in which he also stars, will be the very next film we see here) “The Humbling” is not it.

To be fair, we say through gritted teeth, part of the reason we’ve lingering odium for the film is that while it begins semi-promisingly, and rattles through a first act that is enlivened by some genuine moments where Pacino’s real life and character conflate in potentially fruitful, illuminating ways, from about the midway point all is downhill. So what begins as a fairly engaging, ironic, and intermittently funny portrait of a rueful, despairing man who has lost his talent and his audience and stares hollowly down the barrel of a shotgun that his arms are too short to pull the trigger on, devolves into a shrill, confused mess with unfulfilled ambitions toward grand irony and tragedy. In short, it sent us out into the night unsatisfied and not a little bored.

Pacino plays Simon Axler, who at the film’s start is interminably applying makeup in a dressing room mirror, running his lines and arguing with his reflection about his performance. This is the first hint we get of Axler’s fragmenting state of mind, quickly followed by a scene (which is done no favors by being similar to one in the very great “Birdman”) in which he gets locked out of the theater with seconds to go before his cue. At which point, Pacino wakes up back in his dressing room and we realize all of that had been a kind of fever dream/hallucination (again: “Birdman”). We don’t think it’s spoiling anything to tell you that that rigmarole will happen again, several times over, never to any great effect.

Following a disastrous performance which ends when he throws himself from the stage, Axler swears off acting, and retreats into a suicidal funk in his big, sparsely furnished country house, before his aforementioned short arms provide a reprieve, and he checks instead into a rehab facility for the mentally, um, cuckoo. This place, run by Dylan Baker’s sympathetic shrink is where he meets Sybil (a perky Nina Arianda having ten times more fun than everyone else here) a fellow patient with a fixation on Axler as the person who will kill her husband for her. And the scenes in the institution are perhaps the most interesting in general, as it’s also here that Pacino delivers a long monologue about the pain of losing one’s talents and appetites with age, that is actually genuinely affecting.

But the film’s brief flirtation with that kind of simple, clear-eyed empathy ends when Pacino, cured of his suicidal tendencies, returns to the country house and is called on by Pegeen (Greta Gerwig), the daughter of old friends of his (Dianne Wiest and Dan Hedaya). Pegeen, who had nursed a crush on the famous Axler as a child, is now an adult, and hits on him despite being in a lesbian relationship. Axler responds to the advances of the much younger woman with a kind of baffled gratitude, that soon turns to neediness.

Self-absorbed, mentally unstable and given to quoting Shakespeare at the slightest provocation, Axler is not, by this stage, the most sympathetic of characters (and the hilarious indignity of his back pain is rather heavily relied upon for laffs) but he feels a great deal realer than Gerwig’s Pegeen ever does. To the point that we toyed with the notion that she’s in fact a Tyler Durden-esque figment of his imagination altogether, though we’ve been talked off that ledge, and certainly that’s not the case in the source novel. Still, there’s no doubt that at least some of their interactions are imaginary, but even that doesn’t account for what a perplexing cipher Pegeen becomes; rashly, we’d suggested that after “Frances Ha” Great Gerwig could do no wrong, but turns out she could do “The Humbling.” An unconvincing mix of muse, sexually adventurous dreamgirl (who has suitors of both sexes desperate to get her back) and gold-digger, even her styling changes within the film, as she starts off lank-haired in sloppy hoodies and jeans, but flicks a switch to become a glossily-coiffed and tailored minx, forever removing stiff boutique shopping bags from her convertible VW. It’s a transformation that makes little sense for her character, especially when she basically turns full-on harpy by the film’s borderline unbearable climax in which she and Pacino scream at each other on a stairway for about six years.

Reducing the great Charles Grodin to a couple of scenes, giving Dan Hedaya one, and having Dylan Baker spend most of his screen time nodding sagely via Skype would be understandable choices if the film really was built around the kind of titanic central performance that Pacino will no doubt be credited with here. But is this really the best of him, or is there merely a lot of him (he’s in pretty much every scene)? Certainly, he doesn’t overplay, at least until the end where it seems to be the order of the day, but we have to believe there are much better performances to come from him. Hopefully in much better films than the indulgent and not-near-humble-enough "The Humbling." [C-]